This is a taxation method under Japan's tax system. If you are not a Japanese tax resident, a different set of tax rules will apply to your dividend income.
How it works
Under comprehensive taxation, dividend income is combined with other income, such as salary, and tax is calculated at a progressive rate applied to the total. Investors with lower overall income may benefit from a lower rate, while those with higher income face a higher rate.
Difference from separate self-assessment taxation
Separate self-assessment taxation (see related page) calculates tax independently, at a flat rate, without combining it with other income. When filing a tax return, you may be able to choose either method for dividend income, but which is advantageous depends on your income situation, so please consult a qualified tax accountant.